1. Field of the Invention
The present invention relates to a liquid droplet jetting apparatus such as an ink-jet head which jets liquid droplets from a plurality of nozzles, and a recording apparatus which includes the liquid droplet jetting apparatus.
2. Description of the Related Art
An ink-jet head which jets an ink as liquid droplets has been known as a liquid droplet jetting apparatus. The ink-jet head has a nozzle row which includes a plurality of nozzles and a common liquid chamber to which the ink is supplied from an ink tank. The common liquid chamber extends along the nozzle row and each of the nozzles in the nozzle row is connected to the common liquid chamber via a pressure chamber. In this ink-jet head, the ink is supplied from the ink tank to one end portion, of the common liquid chamber, in a direction in which the nozzle row is arranged, and by applying a pressure fluctuation to the pressure chamber, the ink is jetted from each nozzle as droplets of ink (ink droplets). In the ink-jet head in which, the ink flows through the common liquid chamber from the one end portion to the other end portion, air bubbles which are generated in the ink and grown up are susceptible to be accumulated, and a jetting defect is susceptible to occur in nozzles, in the nozzle row, which are arranged at the other end portion side of the common liquid chamber. Therefore, in a stacked ink-jet recording head described in U.S. Pat. No. 5,748,214A (corresponds to Japanese Patent Application Laid-open No. H8-58086), for example, by arranging so-called dummy nozzles which are not used in an image formation to communicate with a dead end portion of a common ink chamber, and by carrying out a purge operation of nozzles including the dummy nozzles, air bubbles accumulated in the dead end portion of the common ink chamber are discharged.
Moreover, in such ink-jet head, when a pressure fluctuation is applied to a pressure chamber to jet the ink from a certain nozzle, a pressure wave is propagated to a common liquid chamber which is connected to this nozzle. The pressure wave propagated in this common liquid chamber causes the pressure fluctuation of a pressure chamber which is connected to the other nozzle, and causes an unnecessary jetting and a variation (unevenness) in a jetting volume, thereby causing a so-called cross-talk which is a printing defect phenomenon. In order to suppress the cross-talk, in a liquid droplet jetting recording head described in Japanese Patent No. 2815958, an inclined wall or a pocket chamber is formed in an end portion inside a common liquid chamber, on a side where an ink jetting port is not formed, and by causing a pressure wave to be reflected at the inclined wall or the pocket chamber, the pressure wave is attenuated. Moreover, in a liquid droplet jetting head described in Japanese Patent Application Laid-open No. 2004-358737, a partition is formed on a wall surface of a common liquid chamber, and by causing the pressure wave to be reflected or to be resisted, a resonance state of the pressure wave is suppressed.
Inventors of the present invention, as a result of carrying out various experiments regarding such ink-jet head, found that the pressure wave is concentrated at the other end portion, in the direction of the nozzle row, of the common liquid chamber. Moreover, it was revealed that, when there is a plurality of nozzle rows, and there is a common liquid chamber corresponding to each nozzle row, a pressure wave which is generated by jetting ink droplets from a nozzle in a particular row, is also concentrated in the other end portion, in the direction of the nozzle row, of the common liquid chamber corresponding to the other nozzle row. Therefore, a high pressure fluctuation acts on the dummy nozzles formed in the other end portion in the direction of row, and there has been an occurrence of defect that the ink droplets are jetted from the dummy nozzle due to this pressure fluctuation. Due to such defect, undesired ink droplets are adhered to a recording paper etc.